Annex I habitats that are a primary reason for selection of this site

Pant-y-Llyn turlough occupies a small depression on the northern perimeter of the South Wales Coalfield at Cernydd Carmel. This depression represents a glacial channel formed along the Betws Fault where displacement has brought Carboniferous limestone into contact with older Devonian rock. The hydrological regime of the waterbody is linked to local groundwater behaviour within the limestone. The basin fills to a depth of about 3 m during late autumn and remains full until the following summer when it empties completely, thus reflecting the characteristic behaviour of turloughs. There are no surface drainage channels and a swallow hole is located at the northern end of the basin. The basin floor is covered by bryophytes (mainly Fontinalis antipyretica and Drepanocladus aduncus) and herbaceous swamp (water horsetail Equisetum fluviatile and bladder-sedge Carex vesicaria) communities and is surrounded by W3 Salix cinerea – Galium palustre woodland. Within the willow Salix carr, there is a further zonation among the epiphytic bryophytes, with a well-defined Fontinalis community on the lower parts of the trees, which are subject to immersion. The invertebrate fauna is characteristic of seasonal standing waters with aquatic beetles Coleoptera acting as the most diverse group of predators on a microinvertebrate community dominated by relatively large Cladocera and Copepoda.

Annex I habitats present as a qualifying feature, but not a primary
reason for selection of this site